Method of rolling metal



March 4, 19584 L. P. RADER 2,825,251

7 METHOD OF ROLLING METAL Filed July 19, 1952 5 Sheets-Sheet 1 I N VENTOR. [5 Q @4052 March 4, 1958 w 7 L. P. RADER v2,825,251

ME OF O IN METAL.

Filed July 19, 1952 5 Sheets-Sheet 2 172 8.1701 Y P INVENTOR.

March 4, 1958 L. PTRADER 2,

' METHOD OF ROLLING METAL Filed July 19. 1952 Y 5 sneets sneet s a o I34 .96 Q 78 7s 75 45 v o a2 90 74 ffim 78 82 I 70' Y -72 60D INVENTOR..Zss l2 2.9052

- Mam 4, 1958 L. P. RADER 2,825,251 METHOD bF ROLLING METAL F'ilec'lJuly 19, 1952 '5 She ets-Sheet 5 fidfli r1 4 STAT/042v DIE f 1 I I I i(I my 15 L Mow/M0 DIE 5 Q64 3 I V X;

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L I L o I y I I /2 INVENTOR.

United States Patent METHOD OF ROLLING METAL Lee P. Rader, Norwalk,Calif.

Application July 19, 1952, Serial No. 299,7 95

7 Claims. (Cl. 80-60) This invention relates to a method of rollingmetal and more particularly to a method of rolling generally cylindricalor round metal blanks to produce diiferent shapes.

Heretofore, methods have been developed for shaping blanks which arecylindrical or round in cross section to form shapes commonlyexemplified by screws and bolts or the like. Thread forming by rollinghas been confined to the simple displacement of relatively small amountsof metal in the blank to adjacent areas and simultaneously forming athread or other projecting shape during the displacement operation.

However, it has heretofore been impossible to displace relatively largeamounts of metal or to control the direction of displacement by rolling.Where relatively large grooves or outward skirts or other projectionshave been formed; where the metal had to be formed into a particularshape; where a ridge without a groove was desired; or where ridges wereformed with no grooves of less diameter than the blank, it was foundnecessary to machine them. Such operations can be formed in an automaticscrew machine but production with such a machine is much slower and morecostly than production through rolling methods.

.One of two great difliculties encountered prior to my invention inrolling relatively large amounts of metal to displace portions of theblank axially and outwardly, has been due to the fact that the displacedmetal was formed to its final shape during the displacement operation.The other was that there was no way of displacing metal to move in thedesired direction. This resultedv in the need for such excessive inwardradial pressures on .the blank between the dies that the pressuresexceeded the compressive strength of the blank. It also resulted in thedisplacement of metal forming approximately equal ridges on both sidesof the notch and pre- Vented the formation of special shapes. 7

I have conceived a method of displacing relativel large quantities ofmetal by rolling wherein displacement is accomplished in one directiononly or in two controlled directions axially of the blank and whereinthe displaced metal is unconfined during such displacement, therebygreatly reducing the compressive loads on the metal of the blank, butwith the direction of displacement being controlled so the diameter ofthe blank can be held on one side of the groove. I provide a bearingsurface adjacent the displacement surface of the dies to provide thetraction necessary to' displace relatively large quantitles of metal.Also, another form, of my method involves the billowing of metalaxially. Billowing comprises a continuous series of displacementswherein axially displaced increments in turn displace next successiveincrements of metal in the blank. This provides a final ridge or skirtremote from the point where the'original billowing is begun. e

Other objects and advantages of the method will become apparent from thefollowing "detailed description but basically the method involvesdisplacing of metal in Fig. 6 is a side elevational view of the die ofFig. 1; Fig. 7 is a diagrammatic view illustrating the general action ofa pair of dies for practicing themethod;

Figs. 8 and 9 are views of two blanks with the dies in section andindicating a desired example of the angle of attack of the displacingsurface of the die;

Fig. 10 is a plan view of another form of the die;

Figs. 11 through 14 illustrate the steps of forming a shape from the dieof Fig. 10;

Fig. 15 is an end view of a die for the purpose of 1 illustrating adesired angle of displacement surface;

the blank and controlling the direction of displacement Figs. 16, 17 and18 are views illustrating the efiect of variations in the angle of thedisplacing surface of the die;

Fig. 19 is a diagrammatic view illustrating the relative points ofcontact between the two dies and the blank;

Fig. 20 is a view showing an improper relationship between thecomplementary metal displacing ridges of a pair of dies;

Fig. 21 is a view illustrating the proper relationship between theridges on the die with regard to the relative points of contactindicated in Fig. 19;

Fig. 22 is a plan view of a die illustrating in another manner therelative points of contact between two dies and the rolling blank;

Fig. 23 is a plan view of a die with a serration former incorporatedtherewith;

Figs. 24 and 25 are views illustrating the use of'the serrations formedby the die;

Figs. 26 through 31 are illustrative of faults which may be encounteredby the use of improperly shaped dies;

Fig. 32 is an enlarged detail of a portion of a die and showing itengaged in displacement by billowing;

Fig. 33 shows the dies and a blank in the beginning of abillowingoperation;

Fig. 34 is a plan view of a die such as used in billowing;

Fig. 35 is a plan view of the stationary die of a pair indicating thestarting point of the roll thereon;

.Fig. 36 is a diagrammatic view of a pair of dies with the blank at thebeginning of the rolling operation;

Fig. 37 is a plan view of the moving die of the pair in 36 andindicating the starting point thereon.

It will be seen by my drawings that the metal which is displaced by theformation of grooves is moved to one side of the groove while the otherside is held at the original diameter.

Figs. 1 and 6 illustrate a die 70 which is one'of a complementary pairand Figs. 2 through 5 illustrate the action or" dies such as the die 70.The complementary die is shown in Figs. 2 through 5 at 72. The dies haveprojecting ridges 74 and 75 which displace metal to make a groove 76 inthe cylindrical blank 78. This ridge is shown in Fig. 1 to be disposedat an angle to the longitudinal axis of the die and this angle makes theridge 74 very slight at the wall end of the die and at the beginw thatpoint is uniform, and at 7012 the ridge has assumed Patented Mar. 4,1958 a height which beyond that point is uniform. The angulation asshown in Fig. 1 and the gradual increase in height as illustrated inFig. 6 produce a gradual facing of all the displaced metal in-thedesired direction, the blank 78 being held between the dies 70 and 72 insuch a way that there is no axial movement of the blank relative to thedies.

While displacement of metal by rolling might appear, at first glance, tobe a continuous process, each part of the mass of metal being displacedis actually successively periodically engaged by the dies during therolling operation in a series of passes, because the rolling of the Workpiece relative to the dies permits each die to operatively engage only arelatively small peripheralportion ofthe work-piece at. any giventime.This intermittent engagement of the dies with each part of the displacedmass is illustrated in. Figures 19 and 22, and is more specificallydescribed in the following discussion.

When point on the blank or part 78 beingrolled leaves point g on themoving die 70 in Fig. 19, it has been shaped approximately as shown at finFig. 21. Point 1 on the surface of the part 78 will be out of contactwith the dies until the part or blank 78 has been revolved nearlyonehalf revolution when point f comes into contact with the stationarydie 72. By this time, the blank 78having'made its nearly one-halfrevolution, contact with the stationary die 72 is made at point It inFigs. 19 and 22. The point h is a distance farther back on thestationary die 72 equal to nearly one-half the circumference of theblank 78 and will be formed approximately as in Fig. 21. Since theforming edge of ridge 75 is located diagonally on the face of thestationary die 72, the point h (where point f resumes contact) will behigher than point g on the moving die 70. As a result, the angle shownin Fig. 22 at which the forming face of ridge 74 or 75 is disposed andthe angle at which it increases in height must be calculated in a givencase so that when point 1 on the blank 78 comes into contact with thestationary die 72 at point It, there will be sufficient overlapping ofthe ridge 75 on the stationary die 72 and the displaced mass beingmoved. If insufiicient overlapping is permitted or if the ridge is notproperly shaped, the ridge 75 will start a new groove as shown by ridges74a and 75a in Fig. 20.

When metal is being moved in one direction, there is obviously a pullexerted on the neck of the blank which is formed by the groove in theblank. If the part is required to have a deep notch or groove, leaving aneck of small diameter, then axial pull may be enough to cause the neckto stretch or even completely fail under tension. The tendency to dothis can be reduced by properly regulating the angle of the slantedleading faces 80 and 82, Fig. 17, on the leading faces of the ridges 74and 75. Referringnto Figs. 15, 126, 17 and 22, the tendency to stretchthe neck at the notch or groove 76 can be controlled. A method ofcontrol is shown in Figs. 16, 17

and 18 wherein the indicated angles of 30, 45 and 60 are shown on theslanted displacing surfaces 86 of the moving die 70. Where the indicatedangle of 30 in Fig. 16 is used, the approximate pressure exerted is disposed in such a way that the axial tensile load is equal to 86.6 percentof the displacing surface force and the compressive load is 50 percentof the displacing surface force. Where, as in Fig. 17, the indicatedangle is 45, the theoretical applied force is divided equally betweenaxial tension and compression. Where the angle is 60, as indicated inFig. 18, the axial tensile load is 50 percent of the displacing surfaceforce and the compressive load is 86.6 percent of the displacing surfaceforce.

In Fig. 16, the line of arrows SS is at right angles to the metaldisplacing surface 86, showing more of an. axial thrust than that inFig. 17, where the displacementsurface angle is 45 to a planeperpendicular to the axis of the blank 78. In Fig. 18, the line ofarrows 92 shows much more of a transverse compressive force on theblankmamas-1.

where the line of arrows point to the angle of the displacement surfaceis 60 as indicated.

The dies 76 and 72 are shown with grooves 94 and 96 into which thedisplaced metal can flow freely. The grooves are so placed that they liein the natural path of a reasonably unobstructed movement of thedisplaced metal. Referring to Fig. 18, it will be seen that the naturalpath of movement for the displaced metal will be in the direction of acorner 98 of the parent metal in the blank 78. To force a unit ofdisplaced metal past this corner obstruction into die groove 100 willtake con siderably more total pressure than to move the same unit ofdisplaced metal along its natural and unobstructed path quired to.displace'a given unit of metal in the arrange,

ment of Fig. 18 would be considerably greater than the sum of the twoloads required in the arrangement of Fig. 16.

The amount. of pressure which the parent mass can withstand. isgenerally the limiting factor as to how much metal can be displaced andthe rate of such displacement. For this reason, when a 60 angle as inFig. 18 is used, either for the purpose ofreducing the tensile load orfor some otherreason, the rate of penetration of the displacing ridge 74or 75 as well as the degree of displacement must be reduced tocompensate for the added pres sure required, In displacing metal from agroove in the blank to a ridge on the blank, it is generally desirableto apply pressure, as nearly as possible, in a direction at right anglesto the axis of the part.

If the desired finished part requires that the diameter of the blank on'both sides of the groove and the metal displaced therefrom be heldaccurately, and the, tensile strength of the neck or weakest portion ofthe blank is insufficient to safely withstand the axial displacementforce, considerable support' can be provided by the use of lateralridges 104 and grooves 106, Figs. 24 and 25. These ridges and groovesare formed by a similarly shaped part 108 on a die 110 shown in Fig. 23.The ridges 108 on the the 110 need ,be carried lengthwise of the diegenerally ,to the point where axial displacement is completed and, ofcourse, axial tension is relaxed.

The ridges; 104 and grooves 106 on the blank as shown in Figs. 24 and 25are of shallow wave'like form and are such that they can be rolled outsmoothly by a portion 112 of the die llstl'lin Fig. .23.

The depth of the wave-like serrations or grooves 106 in the blank can,for example, be approximately onetenth' of the pitch shown at j inFig.25. A depth of serration of groove 106' in a cylindrical blank, which isthree thousandths to five thousandths of an inch, is generallysufiicient and a pitch j of approximately one-sixteenth inch ispreferred. This. example is given fora small blank whose diameter is onthe order of one-eighth of an inch. Howeventhe figures given above arenot critical but merely exemplary. Ridges or serrations formed asdescribed will ofier substantial support. for the blank againstaxialmovement but will ironout smoothly when the blank reaches the dieportion 112 shown in Fig. 23.

It is generallydesirable that the side 77 of the displacing ridge 74 as'in Figs. 1,. 3 and 4 opposite the direction into which the: displacedmetal is being moved, be wholly :or partially 'at an angle, as in Fig.28, or on a radius 77a asshown in'Fig. 27. Such angle or radius willprevent shaving a thin chip 114 from the upper side of thegrooveias'would occur from the structure shown in Figs.,26 and29 and asis bestillustrated in Figure 29. Such a chip wouldibe pressed into the parentmass and would-.spoihthe appearance: and likely set up incipientfractures underneath it as shown in.Fig.'3l. A sharp corner will alsohave a tendency to crumble and to interfere with proper performance andlife of the die.

It will readily be understood by those skilled in the art that thevolume of metal taken from the groove in the part must be slightly inexcess of the volume of metal required for the ridge on the part. Thisexcess is generally between five and ten percent of the displaced metaland is required because of factors of compression and elongation.Tolerances should always be provided in the dimensions of the groove orthe ridge on the part to enable final adjustment. If too much metal isaccumulated in the forming groove of the die, this excessive metal willform into bulges at the points where the ridge on the part leaves theforming groove in the dies or set up compressive forces which exceed thecompressive strength of the parent mass and cause a compressivefracture, similar in appearance to a pipe in a casting, generallylocated in the core or axial center of the part. If insufficient metalis provided in the forming groove, the ridge on the part will, ofcourse, be incompletely filled and will have a line similar to anincompletely filled thread on a screw. In order to provide asubstantially uniform relation between the volume of metal taken fromthe groove and the volume of metal in the finally formed ridge or collarfor any particular pair of dies, I prefer to use blanks havingsubstantially the same diameter with any particular set of dies.

The method for the axial movement of a thin surface layer of metal intoa solid mass can best be described as billowing the metal. To accumulatea sufiicient mass of metal to produce a substantial ridge by displacinga thin outer layer of the blank, the required area of thin outer layerwould be much too great to be displaced as a unit.

It will be equally apparent that metal from the far end of the outerlayer could not be moved axially for the necessary distance to becomepart of the mass contained in the ridge. These problems are overcome bythe method referred to as billowing the metal. As shown at136 in Fig.33, a narrow strip of the outer layer metal is displaced by radiallyinward pressure upon the periphery of the part. This displaced metal isforced down into the parent mass of metal by pressure from a broadersection 138 of the die in Fig. 33, displacing other metal at that pointas shown at 140. Since each impression of the die reduces the diameterof the part, it can readily be seen that the mass of metal beingdisplaced becomes cumulatively greater. It is also apparent that sincethe mass of metal displaced by each impression is forced back into theparent mass and displaces other metal from the parent mass, it is notitself moved on.

This principle is what makes it possible to accumulate the necessarymass to form a substantial ridge from the 7 thin outer layer.

To provide a continuingly broader pressure point on the dies, as shownat 138 in Fig. 33, the face of the dies may be relieved at an angle asshown at 142 in Fig. 34. In order to avoid folds which would leavespiral lines on the surface of the part, the billowing edge 142 may beshaped at an angle of as shown in Fig. 32. The length of this angleshould be approximately ten percent longer than the axial movement ofthe thickness increase 138 in Fig. 33 in one-half the circumference ofthe part.

The compressive pressure exerted upon the metal to be displaced mustvery nearly approach the compressive strength of the parent mass sinceboth are the same material. It being due only to the fact that thepressure is applied at a concentrated point and is diffused as itrecedes from the point of application, that surface displace ment ofmetal is at all possible. In the displacement of a, small thread uponthe surface of a large parent mass, such as a screw blank, diffusion ofpressure is an unimportant factor. The possibility of a .compressivefailure Of th pat n mass pccurs only. in. such cases where the actualpressure required to form the thread is greatly exceeded. g

In the forming of some of my parts, the opposite is frequently the case.In some experimental parts, made by the methods disclosed herein, thearea in cross section of the metal displaced has sometimes exceeded thearea of the metal remaining in the parent mass by a ratio of 2 to 1. Itis apparent, therefore, that since the mass of metal that is beingdisplaced is so much greater in proportion to the metal remaining in theparent mass, it must absorb much more pressure than is the case in screwthreads or such other forming of this general nature, that precautionsmust be taken in designing the dies, to avoid applying pressures whichwould exceed the compressive strength of the remaining parent mass.

A clearance groove 164 in the die, as shown in Figs. 2 and 3 may beprovided in the area adjacent to the displacement into which the metalmay move freely. This groove should be large enough so there will be noconfinement of the displaced metal moving into it. Any confinement ofthe metal while moving into the groove would add substantially to thepressure required to displace it. Since the displaced metal generallymoves in a direction at right angles to the direction of the forceapplied,'as shown in Figs. l6, l7 and 18, any obstruction to itsmovement would have to be overcome by pressure indirectly applied, sothat it would have to be substantially greater at the point ofapplication than its effect at the point of interference. A roughthinning down of a mass of displaced metal as it is moving into thegroove, as shown in- Fig. 9, instead of permitting it to accumulate inan entirely uncontrolled manner, can generally be 'done if the die isproperly designed without producing more than negligible obstruction tothe moving metal if the groove is deep enough, so that there is noconfinement involved.

If the pressure applying surface 86 in Fig. 16 is at the obtuse angleshown, the displaced metal will tend to move, afterthe initialpenetration, very much as shown in Fig. 6. By the time full penetrationis reached, the mass will generally skirt outward as shown in Fig. 3. Ifthe metal receiving groove is narrow as shown in Fig. 9 and thedirection of application of pressure is not more than 30 measured froman axial line as shown by the lines of arrows in Fig. 8 the applicationof force is sufficiently direct to the axial direction of deformationinterference that it will not prevent successful displacement. If,however, radial confinement were attempted, the direction of theapplication of force would be approximately from the direction of thedeforming interference which is directed radially inwardly, as indicatedin Fig. 9, and would in many cases cause the pressure applied to exceedthe compressive strength of the parent mass.

The final shaping of the ridge to the desired form must generally bedone after the displacement has been completed, and the necessary volumeof metal has been completely placed in the forming groove of the diewhether by the displacement from the groove of the part or by billowingthe metal from the outer shell of the part.

I have illustrated dies for accomplishing both the rough forming andfinal shaping in Figures 7 and 10 to 14, Figure 10 illustrating the faceof one of the dies shown in progressive sections in Figures 11 and 18.v

The most effective method for this final forming depends upon the finalform of ridge or skirt desired on the part. To produce ridges or skirtswith parallel top and bottom surfaces, it is most desirable 'to roughlyformthe metal in the manner shown in Figures 11 and 12, by the methodheretofore described, so as to extend the diameter to a degree greaterthan the desired diameter on the finished part. This permits the packingof the metal to produce a solid smooth ridge by reducingthe depth 7 inthe finishing portions 164 of the die groove 166, as shown in Figs. 7,11, 12, 13 and 14. This not only per- 7 mits achoiceofradii or othershapes on the perimeter of the ridge but is also the most successfulfrom aforming: standpoint.

When the metalis being packed to. producea solid mass with. a goodfinish,uit is under a high degree of pressure. Iftthis pressure wereapplied by bringing the two parallel sides 168 in .Fig. 13 axiallytogether, the grip produced by so .:much pressure applied axially inthis way would be likely toprevent the necessary slippage to compensatefor the difference between the larger diameter of the ridge170 and thesmallerdiameter of the parentpart. Since the part revolves as a unit, itmust be realized-that the surface speed of the two diameters isdifferent and unless'a provision .is made for slippage, the part willbreak either at its weakest point or at the point of greatest strain,

I therefore finish form thepart by bringing bottom portions 172 of diegrooves166 radially inwardly from their relatively large diameter ofFigure 13 to their final, smaller diameter of Figure .14. This reductionof the diameter of the bottom portions 172 of die grooves 166 is alsowell illustrated by Figure 7. This mode of operation keeps slippageinterference at a minimum.

In finish forming ridges of the type which have either one or both ofthe upper and lower sides at an angle, the problem of slippage is notcritical when pressure is applied upon upper and/or lower surfaces.Also, in shapes of this type, where a sharp edge isudesired, it wouldnot be possible to produce the pressure by reducing the diameter. Thereis, moreover, a considerable problem in forcing the metal into a sharpcorner with a small included angle. The method preferred for this formis to apply the pressure from the tapered side or sides, starting toapply the pressure at a point 176 adjacent to the parent mass in Fig.12, and 178 in Fig. 13, and working gradually outward to the peripheryas shown in Fig. 14. Where a saucer shape is desired, the method forapplying pressure is the same as for a conical shape. The differencebeing that in this instance, the side of the groove in the die whichwould be supporting the side of the ridge that is to be hollow, must berelieved to permit a spinning down of the ridge.

The lengths of the two dies in a mating pair for most reciprocatingtypes of thread rolling machines are unequal, the amount of differencevarying with different sizes of machines. This must be taken intoconsideration in design of any dies with a diagonal ridge. Thesemachines are generally so designed that a transfer finger 180 in Fig. 36feeds the part and a starting finger 182 starts the part between thedies at a point generally referred to as the match point in the diesshown at centerline vFigs. 35, 36 and 37. This matchpoint on thestationary or short die islocated at the starting end of the face, asshown by centerline y, Figs. 35, 36 and 37. The proper matchpointon themoving or longer die is properly located by subtracting the length ofthe sta tionary or short die 184 from the length of the moving or longdie 186 and then dividing the length difference by two. One-half of thistotal difference in length of the two dies added to the total length ofstationary or short die provides the dimension for locatingthe the matchpoint on the moving die when measuring from the finishing end of themoving die. The location of the matchpoint on the moving die shouldalwaysbe taken from the finishing end rather than the starting endbecause the finishing end seats against a solid wall in the die pocketand is, therefore, the portion which controls the position of thematchpoint. Thus,,the overhang x on the front end of moving die 186 inFigure 37 is equal to onehalf of the total ditference in length of thetwo dies 184 and 186. A similar overhang of length x (not shown) ispositioned at the other end of moving die 186. No overhang is present ateither end of the stationary die 184. Thus, the diagonal ridges on thedies 184 have the same length v taken from .centerline y and also havethe same width 2 and the same angle z with respect to the longitudinalaxes of the dies 184 and 186. As an we amplero'f the relative dimensionsof the dies 184 and 186, 'and. ofsthedie ridges, if the stationary die184 is four inches long and the moving die five inches long, the lengthvof the ridges onboth dies will be four inches, and thewlength x of theoverhang at each end of the moving die willbe one-half inch.

At 188 in Fig. 36 is shown an end stop of a type well known in theart.It is always advisable to use such an end stop in form rolling whendiagonal ridges are involved, so as to avoid the possibility of startsahead of or behind the propermatchpoint on the moving die. An

improper start is likely to produce a condition similar to that shown inFig. 20.

If the displacement of metal in the required form is extensive, it isgenerally desirable to use the thread rolling machine next larger insize than the one normally used for a screw of the same diameter as thedesired formed part. will do.

Most form rolling dies require a bearing surface, such as at 79 in Figs.2 through 5, on the dies which surfaces bear against the part above andbelow the section being formed. These surfaces may be etched with acidor sandblasted for better traction, but when this is done, the formingridges and grooves should be suitably masked so these parts will retainthe smoothest possible surface. This is necessary to permit the slippagewhich compensates for the difference in surface speed of larger andsmaller diameters on the same unit.

It will, of course, be understood that the method is capable of variouschanges and modifications other than those disclosed without departingfrom the spirit of the invention.

I claim:

1. The method of rolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing an annular shoulder on the blank, engaging said shoulderand progressively moving it axially along the blank with a dieprojection edge disposed at an angle relative to the longitudinal axisof the dies, each point around the circumference of said shoulder beingsuccessively engaged and axially moved by aplurality of successivepasses of said die projection against it as the blank is rolled betweensaid dies, and holding said blank on both axial sides of the metal beingmoved against axial movement of said blank relative to said dies duringthe axial movement of the metal along the blank.

2. The method of rolling a cylindrical metal blank between apairofrolling dies to displace metal axially along the blank, which includesestablishing an annular shoulder onthe blank, engaging said shoulder andprogressively moving it axially along the blank with a die projectionedge disposed atan angle relative to the longitudinal axis of the dies,each point around the circumference of said shoulder being successivelyengaged and axially moved by aplurality of successive passes of said dieprojection against it as the blank is rolled between said dies, holdingsaid blank against axial movement relative to said dies during the axialmovement of the metal along the blank, and shaping the displaced metalby confining it within a die groove after the displacement has beenaccumulated.

3. The method oflrolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing a thin annular shoulder on the blank, engaging said thinshoulder and progressively moving it axiallyalong the blank with adieprojection edge disposed at an angle relative to the longitudinalaxis of the dies to displace a thin outer layer of the metal of theblank axially along the blank, each point around the circumference ofsaid shoulder being successively :engaged and axially moved by a plu Ifdisplacement is limited, the same size rality of successive passes ofsaid die projection against it as the blank is rolled between the dies,said successive passes of the die projection successively forcingincrements of said thin displaced outer layer of the metal back into theparent mass of the blank to successively displace further surfaceincrements of the metal of the blank axially along the blank, andholding said blank on both axial sides of the metal being moved againstaxial movement of said blank relative to said dies during the axialmovement of the metal along the blank.

4. The method of rolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing an annular shoulder on the blank, engaging said shoulderand progressively moving it axially along the blank with a dieprojection edge disposed at an angle relative to the longitudinal axisof the dies, each point around the circumference of said shoulder beingsuccessively engaged and axially moved by a plurality of successivepasses of said die projection against it as the blank is rolled be tweensaid dies, holding said blank against axial movement relative to saiddies during the axial movement of the metal along the blank by formingshallow annular serrations in the blank and operatively engaging thesein complementary longitudinal die serrations, and shaping the displacedmetal by confining it within a die groove after the displacement hasbeen accumulated.

5. The method of rolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing a pair of oppositely directed annular shoulders on theblank, engaging one of said shoulders and progressively moving itaxially along the blank with a die projection edge disposed at an anglerelative to the longitudinal axis of the dies, each point around thecircumference of said shoulder being successively engaged and axiallymoved by a plurality of successive passes of said angular die projectionagainst it as the blank is rolled between said dies, holding said blankagainst axial movement relative to said dies during the axial movementof the metal along the blank by operatively engaging the other annularshoulder on the blank with a die projection edge disposed in substantialalignment with the longitudinal axis of the dies, and shaping thedisplaced metal by confining it within a die groove after thedisplacement has been accumulated.

6. The method of rolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing an annular shoulder on the blank, engaging said shoulderand progressively moving it axially along the blank with a dieprojection edge disposed at an angle relative to the longitudinal axisof the dies, each point around the circumference of said shoulder beingsuccessively engaged and axially moved by a plurality of successivepasses of said die projection against it as the blank is rolled betweensaid dies, holding said blank on both axial sides of the metal beingmoved against axial movement of said blank relative to said dies duringthe axial movement of the metal along the blank, and shaping thedisplaced metal by confining it within a die groove after thedisplacement has been accumulated.

7. The method of rolling a cylindrical metal blank between a pair ofrolling dies to displace metal axially along the blank, which includesestablishing a thin annular shoulder on the blank, engaging said thinshoulder and progressively moving it axially along the blank with a dieprojection edge disposed at an angle relative to the longitudinal axisof the dies to displace a thin outer layer of the metal of the blankaxially along the blank, each point around the circumference of saidshoulder being successively engaged and axially moved by a plurality ofsuccessive passes of said die projection against it as the blank isrolled between the dies, said successive passes of the die projectionsuccessively forcing increments of said thin displaced outer layer ofthe metal back into the parent mass of the blank to successivelydisplace further surface increments of the metal of the blank axiallyalong the blank, holding said blank against axial movement relative tosaid dies during the axial movement of the metal along the blank, andshaping the displaced metal by confining it within a die groove afterthe displacement has been accumulated.

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